The present invention relates to an oil strainer for filtering engine oil used as lubricant in an automobile engine, and to a method of manufacturing such an oil strainer.
An automobile engine is provided with an oil strainer, in which engine oil is cleaned by passing through a filter.
Conventional oil strainers are disclosed in, for example, Japanese Unexamined Utility Model Publication No. 3-119514/1991 (Jitsukaihei 3-119514, published on Dec. 10, 1991) and Japanese Unexamined Patent Publication No. 8-121138/1996 (Tokukaihei 8-121138, published on May 14, 1996). In such conventional oil strainers, as shown in FIGS. 9(a) and 9(b), two synthetic resin partial bodies 81 and 82, are joined together to form a roughly tube-shaped strainer main body 80, the interior of which is provided with a filter (not shown) substantially parallel to the surface where the synthetic resin partial bodies 81 and 82 are joined. The strainer main body 80 is provided with an installation flange 83, by means of which the oil strainer is attached to the engine main body (not shown) opposite an oil outlet thereof. By passing bolts through at least two holes 84 provided in the installation flange 83, the strainer main body 80 is attached and fixed to the engine main body. Incidentally, in some cases an oil strainer is attached directly to an oil pump.
Here, the installation flange 83 is provided so as to project to the sides of the roughly tube-shaped strainer main body 80, such that the holes 84 are located along a line perpendicular to the strainer main body 80.
Recently, however, it is difficult to secure sufficient space in the oil pan to install an oil strainer, and reduction of the space devoted to installation members is needed.
However, in the foregoing conventional oil strainer, since the installation flange 83 is provided such that the holes 84 are located to the sides of the roughly tube-shaped strainer main body 80, it is difficult to reduce the space devoted to installation members.
In addition, since, as also shown in FIG. 10, the installation flange 83 is thin, resin fatigue is likely to occur due to vibration while the engine is running.
A further problem with conventional resin oil strainers like the foregoing is that they lack a sufficient structure for preventing loosening of the installation bolts, because it is difficult to design such a structure.
It is an object of the present invention to provide an oil strainer which can be installed on a small installation surface, which is able to reduce resin fatigue, and which can prevent impairment of the seal due to loosening of installation members, and to provide a method of manufacturing such an oil strainer.
In order to attain the foregoing object, an oil strainer according to the present invention comprises two synthetic resin partial bodies, joined together to form a roughly tube-shaped strainer main body, the interior of which is provided with a filter; and a flange section for attachment with bolts, in which: the flange section is provided with at least one bolt hole which passes through the interior of the roughly tube-shaped strainer main body.
In the fore going oil strainer, the two synthetic resin partial bodies are joined together to form the roughly tube-shaped strainer main body, inside which the filter is provided.
Accordingly, oil flows in through an inlet section of the roughly tube-shaped strainer main body, is filtered by passing through the filter, and flows out of an outlet section of the roughly tube-shaped strainer main body and is supplied to the engine.
The oil strainer according to the present invention has a flange section for attachment with bolts, and the flange section is provided with at least one bolt hole which passes through the interior of the roughly tube-shaped strainer main body.
In other words, the bolt holes of the flange section were conventionally provided so as to project from the sides of the strainer main body, making it difficult to reduce the space devoted to installation members.
However, with the present invention, at least one bolt hole of the flange section is provided so as to pass through the roughly tube-shaped strainer main body. Consequently, at least one bolt hole does not project from the side of the strainer main body, thus contributing to reduction of the space devoted to installation members.
Here, since the strainer main body is roughly tube-shaped, the other bolt hole may be provided in the flange section at the end of the strainer main body, and thus this bolt hole will not project from either side of the strainer main body.
Further, as mentioned above, at least one bolt hole of the flange section is provided so as to pass through the interior of the roughly tube-shaped strainer main body.
This means that the thickness of the flange section is not less than the width of the roughly tube-shaped strainer main body in cross-section.
Accordingly, whereas conventionally the flange section was thin, leading to resin fatigue due to vibration when the engine was running, the flange section in the present invention is thicker, thus reducing such resin fatigue due to vibration when the engine is running.
As a result, it is possible to provide an oil strainer which can be installed on a small installation surface, and which can reduce resin fatigue.
In order to attain the foregoing object, a method of manufacturing an oil strainer according to the present invention is a method of manufacturing an oil strainer comprising two synthetic resin partial bodies joined together to form a roughly tube-shaped strainer main body, the interior of which is provided with a filter, and a flange section for attachment with bolts, in which the flange section is provided with at least one bolt hole which passes through the interior of the roughly tube-shaped strainer main body, and the bolt holes of the flange section are provided with metal guide tubes for guiding and supporting the bolts; said method comprising the steps of: (a) forming each of the synthetic resin partial bodies by injection molding; (b) attaching the filter in the interior of one of the synthetic resin partial bodies; (c) heating and melting surfaces of the synthetic resin partial bodies where they are to be joined; (d) bringing the synthetic resin partial bodies together and joining them to form a roughly tube-shaped shape; (e) a press fitting step, in which the metal guide tubes for guiding the bolts are heated and inserted under pressure into the bolt holes of the flange section; and (f) a pressure fixing step, in which the strainer main body is fixed to the guide tubes under pressure such that the guide tubes protrude from a surface of the bolt holes of the flange section.
In the foregoing method, the steps for manufacturing the oil strainer include (a) forming each of the synthetic resin partial bodies by injection molding; (b) attaching the filter in the interior of one of the synthetic resin partial bodies; (c) heating and melting surfaces of the synthetic resin partial bodies where they are to be joined; (d) bringing the synthetic resin partial bodies together and joining them to form a roughly tube-shaped shape; (e) a press fitting step, in which the metal guide tubes for guiding the bolts are heated and inserted under pressure into the bolt holes of the flange section; and (f) a pressure fixing step, in which the strainer main body is fixed to the guide tubes under pressure such that the guide tubes protrude from a surface of the bolt holes of the flange section.
In other words, the two synthetic resin partial bodies are first formed by injection molding. Then the filter is attached to the interior of one of the synthetic resin partial bodies.
Next, surfaces of the synthetic resin partial bodies where they are to be joined are heated and melted, and the two synthetic resin partial bodies are brought together and joined to form a roughly tube-shaped shape.
Then, in the press fitting step, the metal guide tubes for guiding the bolts are heated and inserted under pressure into the bolt holes of the flange section. Next, in the pressure fixing step, the strainer main body is fixed to the guide tubes under pressure such that the guide tubes protrude from a surface of the bolt holes of the flange section.
With regard to the final positional relationship between the guide tubes and the bolt holes, in order to form a seal, it is preferable if the surface of the flange section facing the engine is on the same plane with the ends of the guide tubes. On the surface of the flange section facing away from the engine, on the other hand, the ends of the guide tubes are on the same plane with the surface, or protrude beyond it. This is to ensure that the guide tubes fully support the bolts.
Further, since a pressure fixing step is used, fixing between the guide tubes and the bolt holes is particularly good when rough finishing (knurling, for example) is performed, and the seal will not be impaired even if the synthetic resin changes over time.
As a result, it is possible to provide a method of manufacturing an oil strainer which can be installed on a small installation surface, which is able to reduce resin fatigue, and which can prevent impairment of the seal due to loosening of installation members.
Additional objects, features, and strengths of the present invention will be made clear by the description below. Further, the advantages of the present invention will be evident from the following explanation in reference to the drawings.